Railway traffic controlling apparatus



May 27, 1941. B. E. OHAGAN RAILWAY TRAFFIC CONTROLLING APPARATUSOriginal Filed June 10, 1958 2 Sheets-Sheet 1 w B0 N T m m r V .T m A ww nw H M May B. E. OHAGAN 2,243,740

' RAILWAY TRAFFIC CONTROLLING APPARATUS Original Filed June .10, .1938 2Sheets-She et 2 INVENTOR flew/251 a Hagan ms Ai'TORNEY Patented May 27,1941 RAILWAY TRAFFIC CONTRGLLKNG APPARATUS Bernard E. OHagan, Swissvale,Pa., assignor to The Union Switch & Signal-Company, Swiss vale, Pa, acorporation of Pennsylvania Original application June 10, (1938, SerialNo. 213,016. Divided and this application August 24, 1940, Serial No.354,080

4 Claims.

My invention relates to railway trafiic controlling apparatus, andparticularly to apparatus for controlling wayside and cab signals bymeans of coded track circuit current.

One feature of my invention is the provision, in apparatus of the typedescribed, of novel and improved means for decoding the coded trackcircuit current.

Other features of my invention will become apparent as the descriptionproceeds.

The present application is a division of my copending application,Serial No. 213,016, filed on June 10, 1938, for Railway trafiiccontrolling apparatus.

I shall describe two forms of apparatus embodying my invention, andshall then point out the novel features thereof in claims.

In the accompanying drawings, Fig. 1 is a diagrammatic view showing oneform of apparatus embodying my invention. Fig. 2 is a view similar toFig. 1 showing a modified form of the ap paratus illustrated in Fig. 1,and also embodying my invention.

' Similar reference characters refer to parts in both views.

Referring first to Fig, l, the reference characters I and l designatethe track rails of a stretch of railway track over which traflicnormally moves in the direction indicated by the similar arrow. Thesetrack rails are divided, by means of insulated joints 2, into aplurality of similar track sections, only one of which, 3-4 is showncomplete in the drawings. Traffic entering each track section iscontrolled by a signal designated by the reference character S with adistinguishing exponent corresponding to the location. These signals maybe of any suitable type but, in the form here shown, these signals areof the color light type, and each comprises a red lamp R, a yellow lampY, and a green lamp G, which lamps, when illuminated indicate stop,caution, and proceed, respectively.

Located at the leaving end of each track section are means for supplyingto the rails of the associated section coded alternating current, the

code frequency of which is controlled by traffic conditions in advance.These means form no part of my present invention and in the wellknownform here shown comprise a track transformer designated by the referencecharacter c T1, with a. distinguishing exponent, the secondary of whichis constantly connected with the rails of the associated section inseries with the usual current limiting impedance 5, and the primary ofwhich is connected with the terminals BX and CK of a suitable source ofcurrent, not shown in the drawings, over the contact [5 of a codingdevice CTi89, or the contact l6 of a coding device CTT5, according asthe front contact l'l-ll or the back contact ll-ll of a relay H which isassociated with the section next in advance is closed, only the codingdevices CT-l5 and CTI80 and the relay H which is associated with'thesection 34 being shown I in the drawings. The coding device CT-l80 isconstantly supplied with current from a suitable source the terminals ofwhich are indicated by the reference characters B and C, and this codingdevice constantly opens and closes its contact I5 at the rate. of 180times per minute. The coding'device (IT-75 is likewise constantlysupplied with current from the terminals B and C, and constantly opensand closes its contact It at the rate of 15 times per minute. It will beseen, therefore, that when the relay H of a'section is picked up so thatits front contact ll-l'h'is closed, the rails of the section next inrear will be supplied with alternating current which is periodicallyinterrupted or coded at the rate of 180 times per minute, but that, whenthe relay H of a section is released, so that its back contact ll-l'l isclosed, the rails of the section next in rear will then be supplied withalternating current which is periodically interrupted or coded at therate of 75 times per minute. The 180 code is used to provide a proceedindication and the '75 code is used to provide the caution indication,in a manner which will be made clear as the description proceeds. Eachrelay H is controlled by traffic con ditions in the associated sectionin a manner which will also be made clear as the description proceeds.

Each track section is provided at the entering end of the section withwhat I shall term a decoding relay of the saturation type, designated bythe reference character DR, only the relay DR associated with section3'4 being shown in the drawings. This relay in the form here illustratedcomprises a main core 6 of the threelegged shell type, and an auxiliaryG-shaped core I which is separated from the one outside leg 6 of thecore 6 by a pair of air gaps 8. The main core 6 is provided with aprimary winding 9 consisting of a single coil disposed on the leg 6 withan input or saturation winding Iii consisting of two coils Hi" and Ndisposed on the two legs 6* and 6, respectively, and connected in seriesin such manner that current flowing in these two coils will cause a fluxto circulate around the closed path formed by the associated legs butnot in the path including the leg 6 and with a secondary or outputwinding I I consisting of two coils II and II disposed on the two legs6* and 6, respectively, and connected in series in such manner that thevoltages induced in these two coils due to flux from the primary winding9 are additive. The auxiliary core I is provided with a secondary oroutput winding I2 consisting as here shown of a single coil.

The primary winding 9 of relay DR. is constantly connected withterminals BX and CX of V the alternating current source, and it will beapparent that with the two coils Ill and III oi the input winding IIIarranged in the manner just described the flux due to the currentflowing in the primary winding will normally not induce any net voltagein the winding I since the voltages induced in the two coils of thiswinding will be equal and opposite. The input winding I0 is energizedfrom the associated track section 3-4 through the medium of 'a relaytransformer RT which insulates the winding I0 from the track rails, anda rectifier R which converts the coded alternating current received fromthe rails into pulses of unidirectional current in winding I0. tionedthat during the on period of the code, the rectified current in windingIII will saturate the portion of the main core on which the secondarywinding II is wound, so that this portion of the core will have a highreluctance for the primary flux. The primary flux will then have a pathof lower reluctance through the air gaps 8 and the auxiliary core I, andthe voltage induced in the secondary winding I2 will therefore berelatively high while: that induced in the secondary winding II will berelatively low. During the off period of the code, however, the inputwinding II! receives no current, and under these conditions, the portionof the core on which the secondary winding II is wound will form a lowerreluctance path for the flux from the primary winding than the paththrough the air gaps 8 and the auxiliary core I, thus causing thevoltage induced in the secondary winding II to be relatively high, andthe voltage induced in the secondary winding I2 to be relatively low;

In order to reduce the power which is required to saturate the relaycore 6, the two legs 6 and of this core may be provided with portions ofreduced cross section between the input or saturating winding I0 and thesecondary winding I I in the manner shown. With the core constructed inthis manner, the current which must be supplied by the track circuitneed only be large enough to saturate these portions of reduced crosssection of the core, and need not be large enough to saturate thecomplete magnetic circuit. When the portions of reduced cross section ofthe core are saturated, these portions of the magnetic circuit are, ineffect, two large air gaps which have a greater reluctance than thereluctance of the physical air gaps 8 between the auxiliary core and themain core. With the ordinary three-legged type of saturation relay, itis necessary to saturate a complete magnetic circuit, which must belarge in order to provide high impedance to alternating current when thecore is not saturated.

The apparatus also includes a decoding transformer DT2 provided with twoprimary windings 21 and 2B and two secondary windings 29 and 30. Theprimary winding 21 is connected with The parts are so proporthe outputterminals of a rectifier R. in series with a resistor XI, and theprimary winding 28 is connected with the output terminals of a rectifierR in series with a resistor X2. The input terminals of the rectifier Rare connected with the secondary winding II of the decoding relay DR,and the input terminals of the rectifier R are connected with thesecondary winding I2 of the decoding relay DE. The resistor XI is alsoconnected with the output terminals of the rectifier R by means of twowires 3| and 32, while the resistor X2 is similarly connected with theoutput terminals of the rectifier R by means of the wire 3| and a wire33, whereby when the rectifier R is delivering current, a voltage willbe impressed on the resistor X2 and when the rectifier R is deliveringcurrent, a voltage will be impressed on the resistor XI. It will benoted that the wires 32 and 33 also serve to connect the two primarywindings 21 and 28 in parallel.

Th parts are so arranged that the pulsating directcurrent which issupplied to the primary windings 21 and 28 from either the rectifier Ror the rectifier R will set up cumulative fluxes in the core of thetransformer DT2, but that the flux which is set up by current from therectifier R will traverse the core of the transformer in the opposite,direction from that which is set up by current from the rectifier R Itwill be seen, therefore, that when coded current, is being supplied tothe decoding relay DR, an alternating voltage will be induced in thesecondary windings 29 and 30 of the decoding transformer insubstantially the same manher as has been accomplished heretofore by adecoding relay having a moving contact, and that this alternatingcurrent will have a frequency which depends upon the code frequency. Thefunction of the resistors XI and X2 and the associated connections is toprovide a sharp cut-01f in the output of each rectifier'R. andjR whenthe current supplied to such rectifier from the associated secondarywinding II or I2 of the decoding relay DR is decreasing. For example, assume that the voltage induced in secondary winding II is increasing andthe voltage induced in secondary winding I2 of relay DR is decreasing,as will be the case'during the ofi period of the code. Under theseconditions, as soon as the voltage from rectifier R exceeds thepotentialdrop across resistor X2 due to the decaying current'fromrectifier R the current from rectifier R will be stopped just as thoughit had been stopped by opening the contact of a relay. In like manner,during the on? period of the code when the voltage in winding I2 isincreasing and that in winding II is decreasing, as soon as the voltagefrom rectifier R exceeds the potential drop across resistor XI due to.the decaying current from rectifier R the output of rectifier R will beinterrupted. It will'be seen, therefore, that with the arrangement shownin Fig. 1 the amount of saturating current fed into the decoding relayfrom the track circuit need not be great enough to completelyv saturatethe relay core, but need only be suflicient to cause, when present,voltage from the winding I I to be less than the voltage from winding I2and, when not present,to"permit the voltage from winding I2 to beslightly greater than the Voltage from winding II.

The decoding transformer DTZ supplies energy to the relay H for section3-4 through the medium of the secondary winding and a rectifier R RelayH is a direct current relay and. is so designed that it will remainenergized whenever transformer DT2 is receiving energy from either the75 or the 180 code The decoding transformer DT2 for section 3-4 alsosupplies energy to a direct current decoding relay J which is connectedwith the secondary winding 30 of the decoding transformer through adecoding unit DUI80.' The details of construction of the decoding unitDU--!8El are not shown in the drawings, but this unit usually comprisesa rectifier and a reactor condenser tuning unit for tuning relay Jwhereby this relay will be energized when and only when the 189 code isbeing supplied to the decoding relay.

When relays H and J are both energized, a circuit is completed for lampof signal S which circuit passes from terminal BX of the source throughfront contact l8--H3 of relay H front contact I 9-| 9 of relay J and thefilament of lamp G to terminal CX. When this circuit is closed, lamp Gis lighted and under these conditions signal S indicates proceed. 'Whenrelay H is energized and relay J is deenergizecl, lamp Y of signal Sthen becomes lighted by virtue of a circuit which passes from terminalBX through front contact l3-l8 of relay H back contact l9l9 of relay Jand the filament of lamp Y to terminal X, and under these conditions,signal S indicates caution.

When, however, relay H is deenergized, lamp R of signal S becomeslighted by virtue of a circuit which passes from terminal BX of thesource through back contact Iii-48 of relay H and the filament of lamp Rof signal S to terminal X, thus causing this signal to indicate stop.

The operation of the apparatus as a whole is as follows: Section 3--4will be supplied with the 180 code or the '75 code according as thesection next in advance is unoccupied or occupied. When section 3-4 issupplied with 180 code "and no train occupies this section, all partswill 00- cupy the positions in which they are shown in the drawings.That is to say, relays H and J will both be energized, the circuit forthe proceed lamp G of signal S including contact lS-lS of relay H andcontact Iii-49 of relay J will be closed, thus causing this lamp to belighted so that the signal will indicate proceed, and the circuit forthe primary of transformer 'IT including front contact l'l-ll of relay Hand contact I of coding device CT-l will be closed so that the sectionnext in rear of section 34 will also be supplied with 180 code.

When section 3--4 is supplied with the 15 code and no train occupiesthis section, relay H will remain picked up but relay J will becomereleased, thus causing signal S to indicate caution. The rails of thesection next in rear of section 3--4, however, will continued to besupplied with 180 code in the same manner as when section 3--4 issupplied with the 180 code and no train occupies this section.

When a train enters section 3-4, the train will shunt away coded currentfrom. the coding apparatus, and relays H and J will then both becomereleased, thus causing signal S to indicate stop. Furthermore, withrelay I-I released, the circuit for the primary of transformer TTincluding back contact 1 1--I'l of relay H and contact iii of codingdevice CT-IS will now be closed, thus causing the rails of the sectionnext in rear of section 3-4 to be supplied with the 75 code.

Referring now to Fig. 2, as here shown the apparatus is similar to thatshown in Fig. 1 with the exception that the biasing resistors Xi and X2have been replaced by two resistors X and X across which separateconstant potentials are maintained by means of associated transformers T'and T and rectifiers R and R The parts are so arranged that the currentwhich is supplied to the primary winding 2! from the rectifier R. willflow through this winding in a direction opposite to that in which thecurrent which is supplied to the primary winding 28 from the rectifier Rflows through this latter winding and the polarities of the rectifiers Rand R, are such as to oppose the voltages of rectifiers R and R It willbe seen, therefore, that the rec-tifiers R and R may be considered asbiasing rectifiers which supply no load except that due to theassociated resistors X and X7. and the purpose of which rectifiers is toprevent current from flowing from either rectifier R. or R when theiroutput voltages are below their biasing voltages which latter voltageswill always bebelow the peak output voltages of the rectifiers R and RIt follows that this arrangement has the advantage of preventing thecontinued flow of current from either rectifier R or R due to theirshort-circuiting action across the associated primary windings 21 and 28when the alternating current supply to them is interrupted or reduced toa relatively low value.

Although I have herein shown and described only two forms of apparatusembodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a transformer comprising two primary windings and asecondary winding inductivly coupled together, means including tworectifiers each connected with a different one of said primary windingsin series with a different resistor for alternately supplying to saidprimary windings pulses of direct current which flow in oppositedirections therein to induce in said secondary winding an alternatingcurrent having a frequency which depends upon the frequency of saidpulses, means for impressing across each resistor a voltage whichopposes that due to the associated rectifier to provide a sharp cut-ofiin the currents supplied to said primary windings, and electroresponsivemeans controlled in accordance with the frequency of the current inducedin said secondary winding.

2. In combination, a section of railway track, means for supplying codedcurrent to the rails of said section; a saturation relay comprising aprimary winding, a saturation winding, and two secondary windingsinductively coupled in such manner that if said primary winding issupplied with alternating current a relatively high voltage will beinduced in the one secondary winding or the other secondary windingaccording as said saturation winding is or is not supplied with directcurrent; means for constantly supplying said primary winding withalternating current, means for supplying said saturation winding withcoded direct current from the rails of said section, a decodingtransformer having two primary windings, means including a rectifierconnected with the one primary winding of said decoding transformer forsupplying it with direct current from said one secondary winding of saidrelay, means including another rectifier connected with the otherprimary winding of said decoding transformer for supplying it withdirect current from said other secondary winding of said relay, tworesistors, means for impressing across each resistor a voltage which isin opposition to that supplied by theassociated rectifier to provide asharp cut-off in the current supplied by the rectifier, and trafficcontrolling apparatus controlled by the alternating current which isinduced in said decoding transformer by the direct currents suppliedthereto by said secondary windings of said relay.

3. In combination, a section of railway track, means for supplying codedcurrent to the rails of said section; a saturation relay comprising aprimary winding, a saturation winding, and two secondary windingsinductively coupled in such manner that if said primary winding issupplied with alternating current a relatively high voltage will beinduced in the on secondary winding or the other secondary windingaccording as said saturation winding is or is not supplied with directcurrent; means for constantly supplying said primary winding withalternating current, means for supplying said saturation winding withcoded direct current from the rails of said section,,a decodingtransformer having two primary windings, means; including a rectifierconnected with the-one primary winding of said, decoding transformer forsupplying it with direct current from said one secondary winding ofsaidrelay, means including another rectifier connected with the otherprimary winding of said decoding transformer for supplying it withdirect current from said other secondary winding of said relay, tworesistors, one connected between each primary winding of saidtransformer and. the associated rectifier, means for impressing acrosseach resistor the voltage supplied by th rectifier which-causes currentto flow in the other resistor, and traffic controlling apparatuscontrolled by the alternating current which is induced in said decodingtransformer by the direct currents supplied thereto by said secondarywindings of said relay.

4. In combination, a transformer comprising two primary windings and asecondary winding inductively coupled together, means including tworectifiers one connected with each said primary winding in series with aresistor for alternately supplying to said primary windings pulses ofdirect current to induce in said secondary winding an alternatingcurrent having a frequency which depends upon the frequency of thecurrent pulses, means for connecting each resistor with the rectifierwhich is not connected in series therewith to at times impress acrosssuch resistor a voltag which opposes that due to the associatedrectifier to provide a sharpcutoff in the flow of current to saidprimary Windings from. the associated rectifier, and electroresponsivemeans controlled in accordance with the frequency of the current inducedin said secondary winding.

BERNARD E. OHAGAN.

